The hypothesis of this project is that cholera toxin B subunit will have mucosal adjuvanticity in humans. The specific aim of this project for the coming year is to determine whether the co-ingestion of a mixture of KLH and cholera toxin B subunit (CT-B) alters the immune response to KLH (secretory immunity or tolerance) in humans. In rodents, cholera toxin is an effective intestinal adjuvant, with the ability to abrogate oral tolerance and promote secretory IgA responses to unrelated antigens. We will determine whether this is true also in humans.